Production of ammonia.



F. HABER & R LE ROSSIGNOL.

PRODUCTION 0F AMMONIA.

Armcmlon man Aue. 1a. 1909.

,202,995, A mme@ oct. 31,1916.

UNITED* STATES PATENT OFFICE.

' FRITZ HABER AND ROBERT LE ROSSIGNOL, OF KARLSRUHE, GERMANY, ASSIGNORS TO BADISCHE ANILIN & SODA FABRIK, 0F LUDWIGSHAFEN-ON-TI-IE-RHINE, GERMANY,

A CORPORATION OF BADEN.

PRODUCTION OF AMMONIA.

Specification of Letters Eatent.I I Patented Oct., 31, 1916 Application sled August i3, 1909. serial no. 512,680.

To all whom t may concern.'

Be it known .that we, FRITZ HABER, Ph.

D., professor of chemistry, andRoBERT LE ROSSIGNOL, bachelor of science, subjects, respectively, of the King of Prussia and the King olf-England, residing at Karlsruhe, Germany, have invented new and useful Improvements in the Production of Ammonia, of which the following is a specification.

Although it is known that on passing a mixture of nitrogen and hydrogen over a.

catalyst at a raised temperature a small fraction of the gases is converted into ammonia, no method. for carrying out this process so as to produce' ammonia on a technical scale has hitherto been discovered (see Zeitschrift fr Elehtrochemz'e, 1907, p. 524). Attempts have been made to increase the quantity of ammonia formed, by withdrawing the ammonia from the gases after they leave the catalyst and then passing the gases thus freed from ammonia again over the cataylst (Zeitschrift fr' Anorganische Chemie, vol. 44E, p. 37 6), but the results Obtained have not led to any technical process being discovered. )Ve have now discovered that ammonia can be obtained from its elements vin a manner which is capable of commercial existence by passing a mixture of nitrogen and hydrogen, or gases containing them (the proportion being .preferably one `volume of nitrogen to each three volumes of hydrogen), over a 'catalytic agent at a high temperature and removing at a lower temperature the ammonia contained in the gases leaving the catalyst. The gases from which ammonia has been removed are then passed over the catalyst again and this may be done by returning the gases to the part of the apparatus containing the catalyst over .which they have already passed and so treating them re* pe'atedly with the lsame quantity/of catalyst. Further, the process must be carried out continuously under pressure and the quantity of ammonia removed fromthe gases may be replaced by an equivalent 'quantity of nitrogen and hydrogen and at the same time the hot gases `leaving the catalyst can be used to preheat the gases from which ammonia has been removed and which are aboutto be passed over the catalyst. In order to effect this regeneration of heat, a small preheater is sufficient, since when the gases being treated are subjected to pressurethe exidly than when the gases are maintained at ordinary.. pressure. Should this transference of heat from the hotter gases to the cooler gases be insuilicient to reduce the temperature of the hotter gases to the degree necessary to enable the ammonia to be conveniently extracted therefrom, additional means of cooling should be employed. The removal of the ammonia from the gases as aforesaid can be effected either by cooling thel mixture of gases containing ammonia until the ammonia state, or the ammonia can be absorbed by means of any suitable absorbing agent, or these two methods can be combined in such a manner that the first, more easily 4condensable portion of ammonia is removed by con-V densation and the remainder is then extracted by means of an absorbing agent. In either case, the removal of the ammonia takes place without the pressure to which the gases are subjected being released. We have further discovered that if-the conditions under which the' process is being worked are such that a comparatively high concentration of ammonia is obtained in the gases leaving the catalyst (for instance by using a very effective catalyst, such for in- 'according to our invention may be as follows: Thecatalyst is 'introduced into a metallic tube to the end of which a heat regenerator is attached. AThe heat regenerator can be of any suitable form, for instance it may consist of a worm tube with a number of narrow. coils, or it may consist of a system of such tubes, or it may merely be a number of Straight parallel tubes. The gaseous mixture containing nitrogen and hy- A drogen in suitable proportions enters the other end of the metallic tube, passes over separates out in a liquid mospheres.

the catalyst, then through the heat regenerator and then through the condenser, absorber, or the like, to a circulating pump. From this pump the gases are returned along the outside of the aforesaid worm or other tubes of the heat regenerator, abstracting heat from the gases contained therein,

paatus is arranged so that the circulation can take place at a suitable pressure. -If desired, the catalyst can be supplied with an amount of heat above that contained in or produced by the system, for instance, electrical heating can be employed. The temperature,` at which the catalyst is maintained varies according to the materiall used and enerally lies, say, between 500 and 1000CJ D. But in employing the expression high temperature herem we do not mean to limit ourselves necessarily to a temperature as high as 500O C.` The pressure can be varied within wide limits, for instance the process can be carried out at a pressure of 150 at- If ya higher pressure be employedy the concentration of the ammonia increases and vice versa. If the liquid ammonia which is obtained according to this example is not used as such, but is converted again into the gaseous form, it is advisable to use the cold produced during its evapora# tion for the purpose of cooling the gases leaving the catalyst.

When gases, other than simply nitrogenand hydrogen in combining proportions are continuously introduced into the system and `the neutral gas or gases accumulate and reach such a concentration ,that the reaction between the nitrogen and hydrogen is adversely affected, the gases should be let out from the apparatus so that the apparatus can be charged afresh with gases as at the commencement of the operation. We vprefer, therefore, always to work with nitrogen and hydrogen as pure as possible and in combining proportions so that the operation need be interrupted as seldom as possible.

The accompanying drawing represents in vertical section any apparatus adapted for carrying' out the process lof our invention.

A is a tube containing the catalytic substance and open at the end a, so as to communicate with the space b, between the tube A and the tube The end a2 of the tube A communicates with the coil c which is inplosed in an outer coil c? so as to leave a .space between the two coils. The coil c2 constitutes a continuation of the tube D.

The coil c is connected by the pipe d with the coil d2 in the cooling 'vessel D, the said coil d2 terminating in a vessel E for the condensed ammonia, a pipe e passing up from this vessel and being connected to the inlet of a circulating pump F the outlet pipe 7 from which communicates with the end c3 of the coil c2. The pipe g having a tap g2 is for supplying to the system nitrogen and hydrogen, `or gases containing nitrogen and hydrogen. For the reason aforesaid, we prefer to supply pure hydrogen and nitrogen in' combining proportions. The supply is, of course, effected at a pressure which will enable the gases to enter against the internal pressure.

t The tubes c, c2 constitute the aforesaid heat regenerator which, together with the tubes or pipes, A andB, are inclosed in the tube H, the whole being strong enough to withstand the pressure employed, the small opening a3 at the end ofthe tube A being to prevent the tube AA being burst by pressure inside it in excess of pressure outside it. Packing of insulating material is filled in between the tube H and the tube B and coil c2, as shown` at I. An electrical resistance wire J is shown wound around the tube B l for the purpose of heating the catalytic subthe valve g2. Then set the circulating pump F in action and apply a suitable cooling agent to the coil d2 in the .vessel D. Hereupon the' greater part of the ammonia is liquefied and collects in E, vwhile the unchanged gases together with a fresh portion of the gas mixture which has passed into the apparatus through the valve G2 are caused to pass once more through the regenerator c2, and the reaction tube A.

We wish it to be understood that the above is only one method of carrying out our invention, and that the invention is not con- `fined to this method, since it is' readily apparent that it can be varied in many ways without departing from the naturel of the invention.

Now what we claim is: 1. The process of producing ammonia by passing a gaseous mixture containing nitrogen and hydrogen over a suitable catalytic agent at a high temperature and removing at a lower temperature ammonia contained in the gases leaving the catalyst, and then again passing the gases from which ammonia has been removed over a catalyst at a high temperature while carrying out the process continuou'sly under pressure and replacing the quantity of ammonia removed from the gases by a fresh quantity of free nitrogen -and hydrogen.

2. The process of producing ammonia by 'passing a gaseous mixture containing nitrogen and hydrogen over-a suitable catalytic agent at a high temperature and removing at a lower temperature ammonia contained in the gases leaving the catalyst and then again passing the gases from which ammonia has been removed o-ver the catalyst by returning them' to the part of the apparatus containing the catalyst already used, While carrying out the process continuously under pressure and replacing the quantity of ammonia removed from the gases by a fresh quantity of free nitrogen and hydrogen.

3. The process of producing ammonia byl passing a gaseous mixture containing nitrogen and hydrogen over a suitable catalyticpassing the gases over a suitable catalyst while carrying out the process continuously under pressure and maintaining substantial uniformity of pressure during the whole of the operations. f

5. The process of producing ammonia by passing a gaseous mixture containingnitrogen and hydrogen over a suitable catalytic agent, removing ammonia from the gases leaving the catalyst while carrying out-the process continuously under pressure.

6. The process of producing ammonia by' passing a gaseous mixture containing nitro-" gen and hydrogen over a suitable catalytic agent, removing ammonia from the vgases leaving the catalyst, and repeating the operation on the uncombined gases while carrying 'out the process continuously under pressure.

7. The process of producing ammonia by passing a gaseous mixture containing nitrolgen andhydrogen over a suitable catalytic agent, removing ammonia from the gases leaving the catalyst and repeating the operation on the uncombined gases while carrying out the process continuously underpressure and maintaining substantial uniformity of pressure during all the operations.

8. The process of producing ammonia by passing a gaseous mixture containing nitrogen and hydrogen over a suitable catalytic agent, removing ammonia as a base from the gases leavin the catalyst, and repeating the operation, w iile protecting the catalyst from sure and replacing the quantity of ammonia removed from the gases by a fresh quantity of free nitrogen and hydrogen and at the same time causing the hot gases leavinoP the catalyst to preheat the cooler gases rom which ammonia has been removed and which are about to be passed over the catalyst.

10. The process of producing ammonia by passing a gaseous mixture containing nitrogen and hydrogen over a suitable catalytic agent at a high temperature and removing at a lower temperature ammonia contained in the gases leaving the catalyst and then passing the gases from which ammonia has ing out the process continuously at a pressure exceeding that of one hundred atmospheres and replacing the quantity of ammonia removed from the gases by a fresh quantity of free nitrogen and hydrogen.

11. The process of producing ammonia by passing a gaseous mixture containing nitrogen and hydrogen over a suitable catalytic agent ata high temperature and removing atv a lower temperature ammonia contained in the gases leaving the catalyst and then passing the gases from which ammonia has been removed over the catalyst, while carry- Ying out the process continuously at a pressure exceeding that of one hundred atmospheres and replacing the quantity of ammonia removed from the gases by a fresh quantity of free nitrogen and hydrogen, and at the same time causing the hot gases leaving the catalyst to preheat the cooler gases from which ammonia has been removed and which are about to be passed over the catal st.

ylQ. The process of producing ammonia by passing a gaseous mixture containing nitrogen 'and hydrogen lover a suitable catalytic agent at a high temperature and removing in a liquid state and at a lower temperature been removed over the catalyst, while carryammonia contained in the gases leaving the catalyst, then passing the gasesr from which ammonia has been removed over the catalyst, while carrying out the process under continuous pressure, and replacing the quantity of ammonia removed from the gases by a fresh quantity of free nitrogen and hydrogen.

13. The process of producing ammonia by passing the gaseous mixtures of nitrogen and hydrogen around a catalyst at a high temperature and into a suitable condenser aty a lower temperature and removin ammonia ,therefrom and then adding to t e gaseous mixture from which ammonia has been extracted a new supply of nitrogen and hydrogen, the Whole of the operations being conducted continuously under pressure.

14. The process of obtaining ammonia by passing a gaseous mixture containing nitrogen and hydrogenunder pressure continuously around and over a catalyst at a high temperature and then cooling saidmixture and extracting ammonia therefrom and add- 4ing to the gases which remain after the exthe diminution caused by the drawing 0H of l the ammonia.

In testimonv whereofr we have hereunto set our hands in the presence of two subscribing witnesses.

FRITZ HABER. ROBERT LE RossiGNoL.

Witnesses:

l J. ALEG. LLOYD, A. RENSLINGER. 

